Validating devices domain
The client uses the CA certificate to authenticate the CA signature on the server certificate, as part of the authorizations before launching a secure connection.
Usually, client software—for example, browsers—include a set of trusted CA certificates.
The quantity of internet browsers, other devices and applications which trust a particular certificate authority is referred to as ubiquity.
Mozilla, which is a non-profit business, issues several commercial CA certificates with its products.
Less often, trustworthy certificates are used for encrypting or signing messages.
CAs dispense end-user certificates too, which can be used with S/MIME.
Worldwide, the certificate authority business is fragmented, with national or regional providers dominating their home market.In cryptography, a certificate authority or certification authority (CA) is an entity that issues digital certificates.